The invention relates to a direct current measuring device comprising at least one first magnetic sensor and at least one second magnetic sensor, said magnetic sensors being sensitive to a magnetic field generated by an electric current flowing in a conductor. The current measuring device comprises a processing unit connected to the magnetic sensors and designed to generate an output signal dependent on the measurement signals supplied by the magnetic sensors and representative of said electric current flowing in the conductor.
The invention also relates to an electro-technical unit comprising a conversion card connected to trip means designed to send tripping orders. Finally the invention also relates to a switchgear unit comprising an opening mechanism for opening electric contacts and a control relay connected to an electro-technical unit according to the invention.